As an important organization of distributed energy resource (DER), the optimized operation of micro-grid is vital to utilization of this technology. Multi-Agent Systems (MAS) is suitable for resolving complicated and open distributed problems, thus occupies certain percentage in micro-grid operation and control utilizing[1].
Currently micro-grid optimized operation based on MAS structure mostly aims at the minimization of cost based on operation and maintenance of network equipment and mutual purchase of electric energy with primary network. The agents normally take voluntary cooperation and cooperate completely with each other to jointly finish the task in solving problems[2]. The existing operation mode has difficult in coordinating interest distribution inside the micro-grid especially when devices therein belong to different owners or when public micro-grid is involved. Current operation and control method of the micro-grid based on voluntary cooperation is subject to interest sharing conflict or difficulty in execution[3].
Power generation bidding method may well reflect the advantages of centralized and distributed control of the micro-grid, and has been practiced in market operation of large grid system [4]. In view of characteristics of distributed energy resources and micro-grid, the following problems should be overcome when adopts bidding in operation of the micro-grid:
(1) As little artificial intervention is imposed to the micro-grid, coordination mechanism between the distributed energy resources may be exploited during bidding process of the energy resource. Global optimized operation of the micro-grid is obtained by multiple feedbacks based on respective “reasonable” bidding under the economic principle of “for myself subjectively and for everybody objectively”. During optimization, the actions of distributed energy resource's bidding results will be directly sent to the micro-grid operation and control agent to perform and therefore, bidding function should be incorporated into entire construction of the operation.
(2) Power generation bidding of the distributed energy resource inside the micro-grid is a complex system and is influenced by various factors such as environment. Distributed energy resources, such as wind energy and solar photo voltaic power generation, have the disadvantages of intermittence and uncontrollability. In addition to the complex operation environment which is difficult to control, it is hard to obtain bidding sample under all modes by means of actual observation or by means of analysis and simulation of actual system. Presently conventional power bidding algorithms such as “reinforcement learning” and “repeat game” are unable to achieve satisfying result of bidding under unknown environment. In the micro-grid, as bidding result will directly guide operation and control, seemingly “reasonable” bidding agent may seem to be “awkward” when facing unexpected events and this is unacceptable.